1. Field of the Invention
This invention generally relates to a bicycle crank arm assembly. More specifically, the present invention relates to a bicycle crank arm assembly having a bicycle crank arm with a pedal attachment bore that has a reinforcement member.
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle as well as the frame of the bicycle. One component that has been extensively redesigned is the bicycle crank arm.
Recently, some bikers enjoy extremely hard riding in the mountains. When riding in the mountains, the various components can often become damaged. One particular component that is sometimes damaged due to such extremely hard riding in the mountains is the bicycle crank arm. Since the bicycle crank arm is rotatably coupled between a pedal and a bottom bracket, the bicycle crank arm often receives very strong external forces from the pedal when the pedal hits external objects such as rocks, trees and artificial objects. Moreover, recently, the bicycle crank arm is made of a lightweight material such as aluminum for the purpose of weight reduction. Consequently, these external forces often cause damages, such as bending and cracking of such lightweight bicycle crank arm.
Therefore, a bicycle crank arm assembly often includes a reinforcement member coupled to the bicycle crank arm at a portion where a pedal axle of the pedal is coupled thereto. This reinforcement member is usually made of a rigid metal, such as steel, to secure the rigidity of a coupling portion of the pedal and the bicycle crank arm. One example of such reinforcement members comprises a bushing member that is inserted in a pedal attachment bore of the bicycle crank arm to be coupled to the pedal axle of the pedal. This reinforcement member includes threads formed on the outer circumferential surface and the inner circumferential surface of the bushing member. The threads on the outer circumferential surface of the bushing member engage with threads on the inner surface of the pedal attachment bore of the bicycle crank arm. The threads on the inner circumferential surface of the bushing member engage with the threads of the pedal axle. In other words, the reinforcement member is threaded into the pedal attachment hole of the crank arm, while the pedal axle is threaded into the reinforcement member. However, since threads inherently have some play, the arrangement of the conventional reinforcement member increases the play of the coupling of the bicycle crank arm and the pedal axle. This play at the coupling section of the crank arm and the pedal often causes damaging of the bicycle crank arm, such as bending and cracking, when the external forces are applied to the crank arm thorough the pedal.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved bicycle crank arm assembly. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.